Question

*Fan & medal* >ONE QUESTION<
Ball 1, with a mass of 10 kg, is moving to the right at 20 m/s. Ball 2 is moving to the left at 20 m/s. Upon collision, Ball 2 comes to a standstill, and Ball 1 moves to the left at twice its original speed. What is the mass of Ball 2?

Answer 1

@Dbzfan836 This is "perfectly elastic collision" right?

Answer 2

yes.

Answer 3

Ok, ima try to figure it out.

Answer 4

Yeah I have no idea how to find the mass. e.e

Answer 5

Wait is the mass 30 by chance?

Answer 6

no.

Answer 7

You find mass by taking the momentum of the object, and dividing that by its velocity

Answer 8

Its momentum is 0 right?

Answer 9

Nvm, 0 is its end velocity.

Answer 10

Alright, to find its momentum, you have to do the same kind of calculations from last time.

Answer 11

Ok so I do 10 X 20 = 200 right?

Answer 12

Don't I need its mass to do the same calculations as last time?

Answer 13

yes, so do all the other object's masses

Answer 14

in the end, what was ball 1's mass?

Answer 15

I mean momentum

Answer 16

in the end, what was ball 1's momentum?

Answer 17

As in any collision momentum is always conserved

Use p total before = p total after

p total after can be found using p = mv (since only one ball is in motion we can ignore the second ball)
p= 10 * 40
=400 kg* m/s

p total after must also be 400

p total before = p ball1 + p ball2
m1v1 + m2v2
isolate for the mass of ball 2
m2= (p total - m1v1) / v2
= (400 - 10(20))/ 20
= 200/20
= 10 kg

Answer 18

dude, you have to let the guy learn from this. You have to let him try

Answer 19

I showed him the work... Was I wrong to do that? Im sorry...:(

Answer 20

Y'all both are helping, ether way is fine. Its just better if someone explains it to me lol.

Answer 21

Okay. My bad....:/

Answer 22

@JahnkeSwim I mean it is wrong to just give answeres

Answer 23

The mass is not 10 though, I have a lab simulation I have to enter the answer in. It says 10 is not right.

Answer 24

alright, did you put 10 Kg?

Answer 25

or just 10?

Answer 26

It automatic puts the kg on it. I have to find the mass of Ball 2.

Answer 27

well, that means we have to start over this, writing it all down to make sure where we were wrong.

Answer 28

Ok.

Answer 29

So this is what we know. Ball 1
Mass: 10 kg
Velocity: 20 m/s

Ball 2
Mass: unkown
Velocity: 20 m/s

Answer 30

yes

Answer 31

Ok so we take 10kg and 20 m/s and multiply it together to get 200 right?

Answer 32

yes

Answer 33

Ok so what next? We don't know the mass of Ball 2 so idk what to do... o.o

Answer 34

alright, what is the mass after the collision?

Answer 35

Idk...

Answer 36

I put in 30 and it says its right, I'm just gonna put 30 as the answer even though I can't show my work. x_x

Answer 37

Thanks for all the help. :)